Method of and means for producing sulphates from mixed sulphide materials and the recovery of values therefrom



Dec. 13, 1932. T, Q CARSON I METHOD OF AND MEANS FOR PRODUCING SULPHATESFROM MIXED SULPHIDE MATERIALS AND THE RECOVERY OF VALUES THEREFROM FiledApril 19, 1950 4 Sheets-Sheet l CGQLER y is r SDI IATID'.

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4 Sheets-Sheet 2 ANWHW n E E? f @nC G. C. CARSON Filed April 19. 1950Dec. 13, 1932.

METHOD OF AND MEANS FOR PRODUCING SULPHATES FROM MIXED SULPHIDEMATERIALS AND TEE RECOVERY oF VALUES TEEREFROM DCC. 13, G Q CARSONMETHOD OF AND MEANS FOR PRODUGING SULPHATES FROM MIXED SULPHIDEMATERIALS AND THE RECOVERY OF VALUES THEREFROM Filed April 19, 1960 4Sheets-Sheet 3 George CdM/sbg# Camo/7 Dec. 13, 1932. G C, CARSON1,890,934

METHOD oEAND MEANS FOR PRoDUcING sULPHATEs FROM MIXED SULPHIDE MATERIALSAND THE RECOVERY oF VALUES TEEREFROM Filed April 19, 1930 4 Sheets-Sheet4 Fi Jia rn-mm( lm-...4

MyW-2 Patented Dec. 13, 1932 UNITED STATESA PATENT orFicE GEORGECAMPBELL CARSON, 0F IOS ANGELES, CALIFDENIA.`

METHOD OF AND MEANS FOR` PRODUCING SULPHA'IES FROM MIXED SULIPHIDEMATERIALS AND THE RECOVERY OF kVALUES THEREFROMv u Application ined,April 19,

Y. My invention relatesto` the productioirof sulphates from miXed orcomplex sulphide materialsI for the segregation and recovery of theirvalues and to the means employed in carrying out the method. While thespecific features of the invention Will be set forth hereinafter, it maybe stated that it comprises the maintenance of a. flowing stream ofAsulphating agent in liquid forml into Which the sulphide materials areintroduced. The strength of the liquid in the stream is maintained andagitation is produced by introducing acid-forming agents,` air or Waterat any point Where needed, and theheat of reaction'and dilution keepsthe temperature at substantially the boilingpoint ofthe liquid. Theattack of the agent upon the sulphides. causes a violent ebullitionWhich helps to agitate the sulphides, with the result that the lighterand more soluble particles tendk to keep in suspension in the stream andto travel with it While the'heavier and more inert particles'settle andare caused to advance' toward the source ot the stream, or counter tothe current iiovv.

Since the sulphides vary in Atheir susceptibility to'a-ttack, theychange into sulphates which are dissolved in different portions of thestream and the sulphates are, for this reason, roughly separated. Whenthe sulphates are dissolved they iioW With the stream vinte regionsWhere they contact with otherl more susceptible sulphides which theyattack and change into sulphates, With the result that they'arethemselves returned to the sul-V phide form and, settling in the stream,are moved back tothe regions Where they Were lfirst sulphated. Thus arethe various sulphates segregated for the recovery of their values byappropriate means and methods.

After the process is brought into full operation, the separatedsulphates may be sold as such; or they may have their base metalsdepositedYelectrolytically; or, with the exception of the sulphates oflead, calcium, barium and the alkaline metals, they may be decomposedinto their respective metal oxides and sulphuric anhydride. All of thesulphuric anhydride thus produced is either fed back into the stream asa replenishing agent or is 1930. Serial No. 445,779.y

accomplished by concentrating lthe sulphurc anhydride in a sulphate',kfromwhichit is dissociated by heat, breaking yavvay from its metaloxide as gaseous sulphuric anhydride which is then combined with Waterto produce the hydrogen sulphate. y

The movement of the heavier p'articlesof the sulphides up the stream andtheir agitation in the liquid keeps their surfaces cleansed andfacilitatesy the reactions, Which continue until the last sulphide thatis susceptible t0 attack goes into solution. Those sulphides andsulphates which do not dissolve are removed from the head of the streamvand are treated for the recovery of theirvalues, as Will be described.

. lVhile the apparatus employed in carrying out my method may be variedin its details, that now preferred is shown in the accompanyingdrawings, in which Fig. l is a flow sheet indicating, inl ageneralmanner, the arrangement of the various instrumentalities trough, as onthe line 4,-4 of Fig. l; Fig.`5 is a horizontal section through thetrough, as

on the line 5-5 of Fig. 4; Fig. 6 is a vertical section through thecenter of one of the terracotta pipes employed in agitating thesulphides in the solvent and for separating the lighter from the heaviersulphides in the stream; Fig. 7 is a transverse section on the line 7-7ot' Fig. 6; Fig. 8 is a longitudinal sectional View on line 8-,8 of Fig.9, showing one of the pipes for introducing iiuids into the stream andfor kcirculating, they sulphides through the pipes shovvn-L in Fig. 6, aportion of the pipe of Fig. 8 being broken away; Fig. 9 is a transversesection, somewhat enlarged, on the line 9 9 of Fig. 8; Fig. 10, is alongi tudinal sectional view through one ot the injectors, Figs. l1 and11a, taken together are a iow sheet. n

In practice, I prefer to flow the sulphating trough or channel, saidagent comprising sulphuric acid (the sulphate oi' hydrogen) and ferriesulphate, both of which are products oi the process. This long troughmay be straight or may be shaped in any manner to meet the conditions ofthe terrain or the buildings where employed, such as superimposing onesection above another section or forming it in a spiral or a series oispirals so as to have a flow of the solution in one direction while thesulphides being soluted are worked in the opposite direction, as will beexplained. The form or arrangement which I prefer, however, is thatshown in the dran ings, in which the trough traverses a field anddoubles back and forth upon itself in such a manner as to provide spacesfor the location of pipe lines', air and gas conduits, tracks,thickeners, buildings and other appurtenances oi the process whereverdesired or needed. The stream has its source at a vessel 10, Fig. l,where washing water is supplied from a source ll. A series oi vessels liie or similar to 10 are employed, the last of the series being shown at12. It is at or adjacent the latter vessel that the first of the acid,or the acid-forming agent or agents, is introduced, and from that pointon to the end of the stream the liquid is maintained more or lessstrongly acid.

The stream flows through a trough or channel, the Walls of which aremade impervious to water or to the acid. From its beginning at thevessel 12 to its tar end at 13, it is inclined so as to cause thesolvent to flow by gravity. It the current were too swift, it would bedifficult if not impossible to propel the sulphides against it by themeans em .ployed The fall of the stream is gentle and as regular as ispracticable.

Starting at the vessel l2, the trough extends for some distance in whatmay be a straight line, as shown; then it tui" s about and iiowssubstantially parallel with its iirst course to a point adjacent thesaid vessel, where it turns again and flows in the same direction as inthe beginning. rlhus, by a series ot turns at each end oi' the field,the stream is caused to flow through a series oi parallel courses,finally ending at 13. The trough in the first course, designated ll, isa single ditch or channel. ln all other places in the stream, the troughis double, one course being separated from the adjacent course by arelatively thin partition. ln Fig. 1, one ot these double courses isdesignated and 16; and Fig. fl shows a section therethrough on the line-fl of Fig. 1, the partition being designated 17. As will be noted, thechannel 16 is slightly lower than is the channel 15 to provide for thefall in the stream. The section is taken adjacent the end turn and thefall in the stream around this turn would be slight, as indicatorl lfthe section were taken near the opposite end of the lield the fall wouldbe quite marked, as will be understood. The outer sides and the bottomof the trough are lined with an acid resistant material, as indicated at18, and the partition l? is 'formed of the same or similar material.This material may be vitrified and placed in position; but, for reasonof economy, I prefer to use alternating coatings of asphaltum and silicauntil a lining of suffe cient thickness and strength is obtained. Thetrough outside the linings may be composed of any material suitable instrength and initial cost, such as concrete.

The adjacent double courses are spaced apart-to ailiord room for tracks19 upon which cars 2U may be run to carry'sulphides from a source ofsupply, indicated at 2l. VT he tracks extend substantially the length ofthe iield and are so arranged that sulphides may be supplied' to thetrough at any point along the courses l5, 1G, and 23, these coursesbeing at or near the middle ot the field. The sulphides are thus` fedfrom the cars at or adjacent the midlength of the stream, although insome circumstances it will be advantageous to feed them elsewhere, aswill be shown, in which case additional tracks may be laid.

The entire field occupied by the trough may be covered, as indicated at24 in Figs. 3 and il, suitable openings 25 being provided through whichthe sulphides are ted. It will usually be suiicient, however', toprovide the cover over that portion oi' the field where the lars 20 areemployed.

A t short intervals throughout the greater part oi" the trough l placethe tubular ele ments 26, shown in detail in Figs. 3, 6 and 7. These areintended to assist in the agitation of the solid particles in the streamand are used wherever there are sulphdes or other matter present whichit is desired be held in suspension. ln Fig. l, the small circlesappearing along the stream indicate these elements, and they are shownas extending from substantially the source of the stream at 12 to andthroughout a portion of the last course which leads to the mouth or" thestream at 13.

They are preferably made of terra-cotta, are

Extending tubular and have a flaring base. across their bottoms aregrooves 27 through which the solvent and the solids may pass to beejected upwardly through the tubular stem. This ejecting action isattained by forcing a fluid, such as S03, HQSOi, air, Water or ferriesulphate ,through a pipe 28 which entends downwardly through therespective tubular element 2G and rests, with a flaring base, upon thebottom of the trough. The pipeQS is closed at its extreme lower end buthas a series of ports 29 extending from the lower end of the tubularpassage upwardly and outwardly through the base portion oi the tube.These ports open above the grooves 2T in the elements 2G so as to directthe fluid against the` inner walls of the latter. This causes the liquidand the solid matter therein to be drawn into the elements 26 and beproj ected up through the latter, thus setting up a circulation whichcauses the lighter particles to rise in tfie liquid above theheavierparticles, the latter settling downto be again and again ejected throughthe elements. j The heavier particles settling down from one elementwill, in part, approach the next element and be injected through it.Thus, in some degree, do these elements assist in moving the sulphidesand other solid particles up the stream.

The pipes 28 are relatively long and they must be made up from somematerial which will not be attached by the acid. Owing to their lengthand small diameter, they must be made strong.. l therefore start with alength of tubing 30 of steel or other suitable metal, and entend throughita glass tube, permitting the ends of the latter to project beyond theends of the metal. The lower end of the metal tube is slit and theprongs between the slits are bent or spread outwardly, as indicated inFig. 9. Another glass tube is placed over the metal tube with its endsprotruding and these protruding ends of the two tubes are fusedtogether, thus fully encasing the metal and protecting it from the acid.rlhe ports 29 extends between the prongs of the metal so that the lattermay not contact the acid.

While, as stated, the circulation of the liquid and sulphides throuO'hthe elements 26 serves in some degree lto advance the sulphides up thestream, this result is attained principally through the use of injectors31, the lower end of one of which is shown in Fig. 10. These injectorsare similar to the tubes 30 in that theyk are long and of small diameterand are strengthened by an inner tubing 32 of steel or similar metalbetween two glass tubes which are projected at their ends and aresealed, thus protecting the metal from the acid. These injectors arenozzleshaped at their lower ends rand are so positioned in the troughthat the air, water, S03, H2804, dissolved F eSOQ, or any other fluid orcombination of fluids projected through them drives the solid materialsup stream. As many of the injectors 31 are used as may be necessary tocause this countercurrent movement of the solids and the liquid. At somepoints it is desirable to cleanse the particles thoroughly and toaccentuate the normal action of theV injectors, as by causing them todrive the sulphides 4and liquids through acid-proof tubular elements onthe bottom of the trough. Such an element is shown at 33 in Figs. 3 and5. The injectors 3l may be extended upwardly at any convenient angle,Fig. 3 showing one at 31a which is almost vertical. Y

The agent or agents above designated,

which are projected through the pipes 28 and injectors 31, may besupplied v.through A,any suitable connections, as through the pipes 34of Fig. 4. These pipes are preferably ex'- tended across one end ofthefield, as indi- 'u' cated in Fig. 1, with branches between the doublecourses of the trough. By suitable valves 35, indicated in Fig. 4, anyof the said agents or any combinations of the same may be admitted toany one of the pipes 28 and fst moved, is discharged at 13upon ankextended and somewhat conical surface which I shall designate thehydrolyzing plain. This plain is shown, in part, in transverse sectionin Fig. 2. In plan view it is circular, except that the field containingthe trough extends into it and occupies a quadrant of the circle, asappears from Fig. 1, the mouth 13 of the stream being` directly abovethe apex of the cone. Thestream flows out upon the top of the cone andspreads outwardly and `downwardly, growing more Aand more shallow untilit becomes a mere film-and finallyceases to flow. A l

The hydrolyzing plain must be carefully prepared to render it acid proofand to prevent moisture from percolating upwardly through it. All soils,sands, rock or other materials having a natural affinity for' ,acid

are to be avoided. The best earth fora silica are rolled down with aheavy road kroller to pack them into place, after which alternatinglayers of acid-proof asphaltum and silica are rolled into place until athick, heavy stratum is formed which is impervious to acid and water. j

Havingprepared the foundation, the low` er gutter or drain 36 is nextconstructed of alternating layers of silica and asphaltum. 1t is given aslightA fall or inclination so that any liquid thereon will flow to oneof its ends, for a purpose hereinafter set forth. The lower segment orstep 37 is formed of the materials just mentioned, but it is laidflat orwithout slope in any direction. It slightly overlaps the gutter 36 so asto deliver any dripe pings from it into the gutter. Theremainingsegments or steps are formed from the same materials,'are laid flat andare arranged in overlapping relation, as shown, until the cap 38 isreached upon which the solution is delivered and from which it spreadsin its descent over the many segments or steps.`

iso

VWhile various groups of vessels, not previously mentioned, areemployed, these will be referred to and their functions set forth in thedetailed description of the method. Enough of the apparatus has now beendescribed to make the method clear.

Mixed sulphide ores vary in their mineral contents and in theproportions in which these contents are present. Thile in some thesulphides of copper, for example, may be abundant, in others thesesulphides may be scarcely more than a trace if any be present. In otherores the sulphides of iron or of Zinc may predominate. The specificmethod of treatment according,r to my invention will de pend somewhat`upon the predominant sulphides in the mixed ores, as will be seen. Forcomplete disclosure, however. it will be assumed that the ore employedcontains substantial quantities of the sulphides of copper. iron, zinc,silver, lead, cobalt. nickel and manganese, with some sulphides ofcadmium. arsenic. antimony and bismuth and small quantities of gold. Theore is first crushed and ground until it is in a finely pulverizedcondition, such as flotation concentrates. This exposes the greatestpossible surface of the sulphides to the acid attack and makes possiblethe develoiiment of the greatest possible mass action. No roasting orother preliminary treatment. except crushing and grinding, is required.

Gil

ln normal operation. the trough is substantiallv open throughout so thata stream of liquid. starting at or adjacent thevessel l2, flows slowlythrough it'to the mouth 13. from which it spreads over thehydrolyzingplain. Near its source the stream is relatively strong in itsacid content and is thus able to sulphate the more highly resistantsulphides. The ores are delivered into the stream adjacent its midlength. The various sulphides differ in their power of resistance to thesulphatngI agent, some being attacked and their sulphates dissolved inthe liquid almost as soon as they enter the stream. The more resistantsnl phides remain longer in the stream and are slowly moved up thelatter until they enter their respective zones wherein the acid isVstrong enough to attack them. The acid grows weaker and weaker as itexpends itself 1n these attacks, except as it is replenished as morespecifically described hereinaft r; but, at the same time, it growsricher and richer in dissolved sulphates.

But, before this normal and continuous operation can be economically7practiced. it is necessary that the trough be properly charged with boththe liquid and the sulphides. l therefore start by forming a pair ofspaced. temporary dams of the sulphides in the otherwise empty trough. Aquantity of the ore is now charged into the trough between these dams,and sulphuric acid and water are worked into the sulphides, the massbeingA kept in a state of agitation by the introduction of air throughthe pipes 28. Various reactions take place, the nature of which will bemore specifically set forth hereinafter.

llVhen the space between the dams in the trough is substantially filledwith the solution, a third dam is formed to provide a space into whichthe overflow from between the first dams may collect. llfhether thisthird dam shall be huilt upstream or down-stream from the first two,depends upon the nature of the sulphides. But before this can be madeplain, it is necessary to know that when a sulphate of a more highlyresistantsulphide is formed, dissolved and is brought into the presenceof a less highly resistant sulphide, the said sulphate is changed to thecorrespendingsulphide which is precipitated. For example, coppersulphide will be precipitated from a copper sulphate solution by thesulphides of Zine, iron or hydrogen in accordance with the followingequations:

lt seen by Equations (l) to that cop per displaces the metal (hydrogenbeingl considered a metal) of the sulphides. Furthermore, the copper incopper sulphate will displace the metal in any sulphide in which themetal has less allinity for sulphur or greater aiiinity for oxygen thanhas copper, and the copper will become copper sulphide while the metaldisplaced becomes a sulphate. Copper sulphate, therefore, aids in theattack upon any of these sulphides.V For eX- ample, in Equation Ll, theSQl radical de'tachcs itself from the Cu of the sulphate and at tachesitself to the lil! of the sulphide, while the S of the sulphide attachesitself to the Cu` of the sulphate, thus bringing about what is termed adouble decomposition. Because of the foregoing, copper sulphate becomesdepleted from the solution as the solvent progresses into theundissolved mixture of sulphides and the copper is precipitated as asulphide.

lllhen, therefore, copper' sulphate in considerable quantity is in theliquid between the first two dams, the third dam is formed upstream,since, in the normal and continuous operation of the method, the coppersulphidcs are not sulphatcd until they are near the head of the stream.if, on the other hand, the sulphides are of a nature to change all thecopper sul )hate to sulphides, in accordance with Equations to the thirddam is formed down stream, since it is evident there is comparativelylittle copper in the ore. The liquid between the first two dams is thenlil() lli) allowed to flow into the space formed by building the thirddam.

This work of constructing temporary dams and filling the spaces iscontinued until a sufficient length of the trough is occupied toestablish conditions required for the practice of the continuousprocess. Then all of the dams are broken out and the injectors 3l arebrought into action to sweep the residues from the dissolved materialsand the more resistant sulphides toward the vessel 12, while the liquidcontaining some of the dissolved sulphates flows out for crystallizationor hydrolyzation upon the hydrolyzing plain.

As stated, the stream has its source at the vessel 10 where Wash waterfrom 11 is supplied. Water from 11 is also conducted through one of thepipes 34, from which it may be discharged into the trough at any desiredpoint, as is indicated in Fig. l by the arrows on the lines which branchfrom said pipe. The acideforming agents heretofore mentioned areconducted through the other pipes shown at the right in Fig. l and are fdischarged into the liquid at any desired part of the trough. Thereactions are eXotherniic, and the acidforming agents are introducedwhere and in such quantities as to give the requisite strength to thesolvent and to maintain the temperature of the latter at approximatelythe boiling point. When water is added, the heat of dilution aids inmaintaining the desired temperature.

Assuming that the ores contain substantial quantities of the sulphidesabove mentioned, they are introduced into the flowing stream at thecentral courses l5, 16, 22 and 23. The finer particles of the sulphideswhich are most susceptible to attack are quickly sulphated anddissolved, liberating heat, forming HZS, and setting up a violentebullition which agitates the sulphides and causes the more soluble andlifrhter particles to rise and effervesce, while tie heavier and moreinert particles settle down in the trough, being advanced up-stream bythe fluids introduced through the injectors 31 and being continuallyagitated by the fluids introduced through the pipes 28. The movement ofthe particles, due to the agitation and the upstream advance, keeps thesurfaces of the particles washed clean and in the most favorablecondition for yielding to the acid attack.

While the finer particles of the sulphides of zinc, iron, cadmium, etc.are quickly and completely oxidized and dissolved` and their sulphatespassed down the stream, the coarser particles remain longer and aremoved a con siderable distance up-stream before they7 finally disappear.This brings some. of them into the Zone where the acid is strong enoughto begin its attack on the copper sulphides. At a point 39 in the firstcourse 14, where it is assumed the dissolved copper sulphate becomesabundant, a portion of the stream is Vthe scum.

shuntedout for special treatment. This feature will be more specificallydescribed later and is here referred to in order to locate thecopper-sulphate Zone. The copper sulphate formed and dissolved below thesaid point 39 flows down the stream until it meets some of the sulphideswhich are more easily sulphated, where it is desulphated and the copperprecipitated in sulphide form, in accordance with Equations (l) to (4).These precipitated sulphides join the other sulphides and solids in thestream and are'moved back into 'the copper sulphate zone where they areagain sulphated. This cycle, which comprises sulphating the coppersulphides, dissolving the copper sulphate, flowing the latter downstream, desulpha-ting it, precipitating the copper sulphides and movingthe latter back into the copper sulphate zone, may be repeatedautomatically over and over again, with the result that the coppersulphate is concentrated inits zone and is in condition for treatmentforL the recovery of its copper content. The more easily sulphated partsof the ore have been attacked and their sulphates flowed down the streamwhile the more resistant parts are movedV farther up stream, therebyleaving the copper sulphate substantially isolated. y

Since the special treatment of the copper sulphate after it has beenshunted from the main stream involves the use of ferrous sulphide (FeS),I shall now state how the latter is obtained. c

Among the various sulphides of iron in the ore there is usuallyaconsiderable quam tity of the primary pyrite (FeSg). When the sulphidesare dumped into the stream and the reactions have somewhat subsided,this pyrite. will be found fioating as a scum uponV with suitablefloats, as at 41a, to hold back The scum is led to va heater 4l wherethe feeble atom of S is driven off, leaving FeS, which is collected at42. The S is passed through a condenser at 43 and is collected as aproduct at 44.

' When there is a considerable quantity of copper in sulphide form inthe ores, little attention need be given to the copper sulphate,

since it will automatically collect in its propn er zone in suicientamounts for individual treatment. But when there is only a small amountof the copper sulphides, their sulphatization is retarded by theintroduction of fresh ore or iron sulphide into the Stream. The morereadily attacked sulphides in the ore or the iron sulphide thusintroduced will protect the copper sulphides from the acid attack; or,if some of the copper sulphides have become sulphated, the addedsulphides will attack these sulphates and precipitate the coppersulphides, which sulphides will be earried farther up the stream to apoint where they have concentrated in suicient quantity to warrant theirsulphatization, which may be effected by injecting,r sulphuric anhydrideinto the accumulated copper sulphide muck. In this simple manner, thecopper sulphate may be concentrated in its proper zone, which is assumedto be at or adjacent the point 39, as stated. If the copper sulphate bein sufficient quantity and of sutlicient purity to warrant it, a portionof the liquid may be diverted at once to electrolytic cells for therecovery of the metallic copper, the electrolyte beingr returned to thestream to help in maintaining the strength of the solution. If thesolution does not contain enough copper sulphate to warrant this directtreatment, a part of it is shunted out at 39 and passed intothiclrenvers 45, into which enough of the FeS from #l2 `is fed to reactwith the HLSO.l and produce HES, as follows:

(5) FeSwLH2SOl=FeSO4+II2S This ILS reacts with the copper sulphate tochange it to the sulphide in accordance with Equation (et). Also ILS,produced in redis solving the CnS precipitate, may be employed inprecipitating copper sulphide for removal from the stream at any placeWhere its removal is desirable.

The ferrous sulphate of Equation goes into solution and, overliowingfrom the last thickener, is diverted back into the stream, as at 46. Theprecipitated and thickened CuS is filtered and washed at 47 and thefiltrate and wash water are returned to the stream, as at 48. The filtercake is transferred to the vessels 49 where the CuS is again sulphatedand dissolved by injecting SOS and water or by the addition of sulphuricacid, I-IQS beingformed by the reaction. The vessels 49 are preferablyhooded or otherwise constructed to collect this IIZS, which may be usedat any point in the process, as is indicated in Fig. 11 of the flowsheet. From the vessels 49, the copper sulphate is passed to theelectrolytic cells 50 where the metal content is deposited aselectrolytic copper, the spent electrolyte being returned to the stream,as at 51.

Vhen a sulphide is attached by the sulphuric acid, hydrogen sulphide isformed, as is shown by Equation (5), which is typical. Vhile this ILS isa gas, it is absorbed in the liquid and, if not removed, it seriouslyinterferes with the reactions. It reduces the sul* phates alreadyformed, as in Equation (4) or it prevents the sulphates from forming.Further, there are some complex copper sulphides containing antimony,such as tetrahedrite (CuSSbgST), or arsenic, such as enargite(Cusr-isSl), which, while readily oxidized by HgSOr when the resultingHES is removed,

are very slowly attached by that acid when the IIQS is allowed toremain. This is for thc reason that, as the ILS is formed, it attachesitself to the sulphide particles and surrounds them as an envelope orfilm, thus insulating;v them from the acid. This results in the saidcomplex sulphides being; carried up stream far beyond thecopper-sulphate zone before armor-1),Jesi-nso,L

It attacks the ILS with which it contacts, the reaction being' shown bythe following:

7) re,(sol)i-ngseareso@inson-s Thus, not only is the I-IZS removed, butthe acid is strengthened by another molecule of HQSOL. Further, as hasbeen stated, air is added through the pipes 2S and injectors 8l whereverit may be needed; and its addr tion to the QEeSO4 and the HgSOi producedby Equation (7), gives back the ferrie sul phate. Thus,

O2: areasoneafengo As has been stated, the treatment of the CuSOi withthe FeS in the thickeners @l5 results in the formation of IeSOi, whichis discharged into the stream, as at 4:6. This becomes one source of theferrous sulphate from which the ferrie sulphate is produced, as shown inEquation But there are numerous other sources. Equation (3) shows, FeSO,is produced when the FeS.l in the ore is attached by the CuSOi. Further,such of the iron pyrites (FeS2) as go into solution are acted on to formferrous sulphate, the following` representing an outline of what occurswithout consideration of the exact mechanism of the reactions The sameis true of the pyrrhotite (FeTSS), as is here shown:

introduced to form the ferrous sulphate, as follows:

(1l) CuFeS2 -t 8O :EeSOi-l- Cu SO,l

The sulphide bornite (CuEeSQ may also be present in the ore tocontribute to the lCt free.

Vthe sulphur.

ferrous sulphate produced. In carrying out the process disclosed hereinin which the solution is strongly acid and an excess of oxygen ispresent, the reaction would be as follows:

(12) CulfeS4 -i- 2H2SO,t -I- 180 CuSO., -t FeSOil- QHZO If the solutionbecomes weal; in acid, H253 will be formed; but in practice such a weakcondition should not bel permitted to obtain.

This equation shows a production of six molecules of sulphate at theexpenditure of but two molecules of acid.

The reactions of Equations (9), (l0), (11) and (12) may be brought aboutat any point in the stream where any pyrite, pyrrhotite, chalcopyrite,or bornite, is present by the in jection of air through the pipes orinjectors. lf ferrie sulphate in sufcient quantity to rid the solutionof HES is not produced in the several ways stated, or if it be requiredto some point where it cannot be supplied in any of said ways, it may beobtained by diverting a part or all of the overflow of Fes-JO, from thetliicleners Zl5 t-oa storage tank at 52 and there treating it withsufcient HQSO., and air to convert it into ferrie sulphate in accordancewith Equation Or, water may be used instead of the HgSOi, as follows:

The hydroxide thus produced may be filtered out leaving the ferriesulphate, which, whether produced in accordance with Equation (8) or(13), may be introduced into the stream wherever required, as isindicated by the line connecting the tank 52 with one of the pipes 34(Fig. 1).

In addition to removing the B2S from the stream, the ferrie sulphatereacts with other compounds in the ores and facilitates the operation.It attacks the pyrrhotite and the pyrites and produces ferrous sulphate.Thus,

In each of th-ese reactions, as well as in Equations 2 and Y, elementalsulphur is set This forms a sludge in and travels with the solution. Itis removed before the liquid is treated for the recovery of the valuesfrom the more easily formed sulphates. Tf the sulphur and other mattersforming the sludge become so thick in the stream as to protect thesuspend-ed sulphides from the acid, the stream is passed through at-hichener to remove the sludge, and the latter is then destroyed bycrystallizing and distilling olf The remaining parts of the sludge maythen be treated to recover whatever may be of value in them. The ferriesulphate, if introduced in suflicient amount and in the proper parts ofthe stream, assists in the removal of this sulphur and, in so doing,furnishes an additional supply of ferrous sulphate and sulphuric acid.This 1s shown by thefollowlng equation:

A still further supply of ferrie sulphate comes fromV the hydrolyzingplain of Fig. 2, as will be seen.

Thev sulphides and other solid materials in such substances as cobaltite(CoAsS),ymilly erite (NiSf), sphalerite (ZnS), alabandite (MnS) andgalena (PbS), which occur `in many mixed sulphide ores, typicalreactions being` shown by the following equations which afford atheoretical explanation of the reactions:

( 17) QCoAsS -l- 110 2 QCOSO., l- AsQOG,

(18) NiS+4O=NiSOn l Since the solution is maintained at subst-antiallythe boiling point, it dissolves more of the sulphates than it can carryin solution at lower temperatures. If the sulphates should float downstream to a point where the kheat of reaction is not sufficient t-omaintain the 105 temperature high enough to hold all of them in solutionand some begin to crystallize on the sides and bottom of the trough,more sulphuric anhydride is added at that point to raise the temperaturethere, thus to hold me all the sulphates in solution.

If, on the other hand, thesolution should become too hot, the primarypyrite (FeSg) floating on the steam gives upits feeble atom n of Swhich, combiningr with oxygen, produces the noxious SO2. This nuisancecan `be abated by skimming off the hot pyrite into a solution of ferriesulphate, or by supplying a liberal quantity ofthat sulphate with someair to the stream to react with the SO2, as follows: f

From the above, it will be appreciated that ferrous sulphate, which maybe obtained from various sources` performs a most important part in mymethod and that it'may 'be introduced into the stream at anydesiredpoint and there oxidized into the ferrie sulphate by dit" theinjection ot' air, as in Equations (8) and (13). However, I prefer tooXidize the ferrous into ferrie sulphate outside the stream and thenintroduce the sulphate into the stream when needed.

After the copper has been removed from the solution, as above described,there remain in the upper end of the stream the sulphides and sulphatesof silver, lead and gold, as Well as any insolubles, such as SiOg, alloi' which have been advanced up the stream by the fluids deliveredprincipally through the injectors 3l. 0f these remaining sulphides, thatof silver is the most susceptible to the acid attack, and the silversulphate zone follows neXt after that of the copper sulphate. Forpurpose of description and illustration, it Will be assumed that thesilver sulphides are sulphated in the iirst course ot the troughadjacent the head of the stream at l2.

After all the copper sulphides have gone into solution, the mud and allthe solid particles are violently agitated with sulphuric anhydride andenough ferrie sulphate to oXidize'any H28 present. he liner particles otthe silver sulphide are readily sulphated and the sulphate iioived downstream to be changed to the sulphide again by contacting with the copperor other sulphides there. Then these silver sulphides are moved back upstream into the zone Where they were first sulphated and Where the acidis strong, all as has been described in connection with the coppersulphides. Thus is the silver sulphate accumulated in the stream in itsproper zone, the more readily attacked sulphides having been sulphatedand their sulphates flowed down the stream While the lead, the gold, theinsolubles and the residues have been moved farther up stream.

At the point ot greatest concentration of the silver sulphate, a portionof the stream is shunted out for special treatment in the recovery ofthe silver. In Fig. l` this point is assumed to be at 53. The liquidthus shunted is led through thickeners at 54 While still hot to removeall undissolved materials therefrom, after Which the clarified liquid ispassed through copper shavings at 55 to deposit out the silver, theremaining solution being then returned to the stream at 56. The silvermay be precipitated by other known means if preferred.

It the sulphides are of such a nature as to hold the silver insoluble,or if the quantity of silver in the sulphides is so small as to make itimpracticable to recover it by the method just set forth, then all ofthe silver is retained in the residue by charging a small quantity ofiron sulphide into the mud at the bottom of the stream, after which thesilver is recovered as presently described.

At the head of the stream, all the solid matter is ejected, as throughone of the tubular elements 33, (F ig. 3), or is otherwise transferred,into the vessel 12, Which is the last of the series of Washers. From thevessel 12 to the first of the series at l0, the said matter istransferred counter to the current of Water therethrough and the solidsare thus thoroughly cleansed and made ready for the next step in theprocess.

At 57, F ig. l, there is shown a tank containing a hot solution of salt,(NaCl). This brine is supplied to and is caused to loiv through a seriesof thickeners 58--58a into a large thickener 59 adjacent the Washers l0.Chlorine is charged into and agitated with the hot brine in thethickener 59 until the brine becomes saturated with it. The overflowfrom this thickener passes through a series of boxes 60 containingcopper shavings, for a purpose hereinafter stated, and thence into acooler at Gl. From this cooler the brine is conducted back to the tank57 or to the connection therefrom which leads to the thickener 58. Thebrine is, therefore, in a closed circuit and is passed therethrough anynumber of times, its strength being maintained by salt added to the tank57. Preferably, the flow from the tank to the cooler 6l is by gravity.The brine may be heated in any suitable manner.

The solid materials from the Washers l2 and l0 are passed into the largethickener 59 containing the chlorine-saturated brine, which is hot.There the lead sulphates are converted into lead chloride; and, if thesilver has been caused to remain with the residues, as above described,it Will likewise be converted into silver chloride. These chlorides gointo solution, and the overflow from 59 is passed through the coppershavings in the vessel 60 to precipitate the silver, Which may then berecovered. The hot solution of lead chloride is then cooled andcrystallized at 6l, and the lead is recovered, as by electrolysis in thecells 62, the metallic lead appearing as a product at G3. Any chlorinethat escapes from the saturated brine or is set tree in the cells 62 maybe returned to the brine circuit, is indicated, or any eX- cess oi' itmay be made into chlorides or hydrochloric acid. l

The thickenings ot' the thickener 59 are passed through the series ofthickeners 58u- 58 Where they are agitated and moved upstream, in anysuitable manner, until all the lead sulphate has been dissolved andreturned to the thickener 59 as lead chloride. The thickenin of the lastthickener 58 are filtered and Washed at (ifi and are made ready tortreatment for the recovery of gold. lVhile any suitable method may beemployed for this treatment, l prefer and have indicated the cyanidemethod which will be discussed but briefly.

At 65 there is maintained a supply of cyanide solution which isdelivered to a series of pachuca tanks 66--66a through which it floats41 and the floating pyrites have been i skimmed, it has accumulated aconsiderable quantity of sludge which may have so entangled someV of thecopper sulphides as to have carried them kdovvn'the stream. In such casethe stream is diverted, as at the point 69, through thickeners to removethe sludge, the clariiied liquid being passedr back into the trough, asat 71. The thickenings may then be transferred to ythe copper-sulphatezone of thestream and the copper therein recovered, as has beendescribed, or the sludge may be separately treated for the recovery ofits copper.

After passing the said floats 4l, nomore ore is added, but the stream iskept hot by the introduction of acid or acid-forming agents, preferablysulphuric anhydride, in order to prevent the sulphates fromcrystallizing. Many of the reactions set forth continue until all thesulphides Which are light enough to travel with the stream or Which havebecome entangled in the sludge have been sulphated and dissolved. Thestream is then heavily charged With sulphates of iron, Zinc, nickel,etc., and contains some sulphates of cadmium, arsenic, antimony andbismuth.

' These latter sulphates may now be removed by the introduction of FeSfrom 42 into. the stream, as at the point 72. This FeSA reacts with theacid, in accordance with Equation (5), to form ILS; and this ILS reactswith the sulphates of cadmium etc., as in typical Equation toprecipitate the metals as sulphides. rlhe stream with these precipitatedsulphides is now'diverted, as at 7 3, into a series of settlers andthickeners 74 and through a filter at 75 Where the precipitates andsludge are removed and transferred to a storage chamber 7G to be treatedin any suitable manner for the recovery of such metal values as they maycontain, the filtrate heing returned to the stream, as indicated at (Ca.

As stated, the FeS used in the precipitation of the cadmium etc. istaken from the storage chamber 42. Since this FeS has been derived fromthe scum of 4floating pyrite, it

may contain a substantial amount of Vcopperv sulphides Which had becomeentrapped inthe sulphides. I accordingly prefer flrst to treat f the FeSto generate HZS, as ink Equation (5) The HZS is then introduced into thestream to precipitate the cadmium and kindred sulphides which areremoved at 74 and 75, as described. f Or, ILS produced in redissolvingVCnS for the production of CuSO4'to be emr ployedv in the production ofelectrolyticy copper may alsobe employed in precipitating thesesulphides. It may also be used in the thickeners 45 instead oi' FeS, asis obvious;

These sulphides being removed, the principal sulphates remaining arethose of iron, zinc, nickel and cobalt. The most economi- `cal methodnovv to befollowed for the recovprecipitatingit asihydroxides. Iaccordinglyv divert the stream, as at 77, through a series of digesters78-1nto which I introduce a suiflcient amount otzinc oXide to hydrolize`the iron' and form zinc sulphate according to the following reactions:

(20) FeSOi-rHgO'ZnO:

(ai) rensoniernowzno: s

The zinc sulphate thus produced goes into solution, While the ironhydroXides may be filtered out at 79 and deposited at 80,` the liquidbeing returned to the trough, as at 8l.

The zinc sulphate obtained from the zinc sulphides in the ore and fromreactions (20) `and (21) is now treated for the production oi the S03for use in the streamto maintain the 4acid strength and the heat.Iffmore S03 is thus produced than isy necessary for tiiese purposes, thesurplus amount is used in the production of H2SO4. Accordingly,

the clear liquid from the lter 7 9 is run out upon the hydrolyzing plainof 2 Where the zinc sulphate is crystallized. A portion of the crystalsare then dehydrated and dissociatedinto zinc oxide and S03, thetemperature employed in dissociating being maintained lowy enough toprevent the `S03 from breaking up into SO2 and O. The zinc oxide thusVformed may be used in the digesters 78,

While the S03 is conducted tothe appropriatey pipe 34 to beldischargedinto the Lstream. rEhe remaining portionof the'kzinc sulphatecrystalsmay be dissolved and run into electro- 'lytic cells for thedeposition of zinc, thespent electrolyte being returned to the stream.

' lVhen-fthef liquid from the digesters`7 8 and filters 79 containssulphates, such as nickel andv cobalt sulphates, in quantities 1 largeenough to interfere with the el-ectrolytic depositionof the Zinc, thesolution is switched out of the-'trouglnas at V82', through a series ofdigesters 83 into which a large amount of zinc oxide is fed. The liquidis thoroughly agitated and the said sulphates are converted into theoxides of the metals which are deposited. These oxides are permitted toaccumulate in the digesters until a sufficient amount is present toWarrant their treatment for recovery of their metal values. Thereactions of the nickel and cobalt sulphates with the zine oxide are asfollows:

(22) NisonsznoNioJfZnSOi,

(23) CoS0i-I-Zn0 000 ZnS'04.

Such portions of the zinc sulphate as are required to produce thenecessary S03 are returned to the stream, as at 84, and run out upon thehydrolyzing plain for crystallization, dehydration and dissociation, asabove described. The remaining part of the zinc sulphate solution ispassed through a filter at85 and is then discharged into electrolyticcells at 86 for the recovery of the metallic zinc, the product, Zn,being indicated at 86a'.

fofiron, zinc and other soluble basic sulphates yare gathered up fromthe plain and dehy drated at 87. Then the dehydrated mass is `passedthrough dissociators 88 in which the temperature is so controlled as todissociate onlythe ferrous and ferrie sulphates, producing thecorresponding iron oxides and sulphuric anhydride. The latter isconducted through 89 toits pipe 3ft for introduction into .the stream,as has been described. The resulting iron oxides and the remainingsulphates are Washed at 90 With Water from 91 to dissolve the sulphatecrystals and leave the iron oxides. The sulphate solution from 90 `is.then passed through 92 to the electrolytic cells 86 for the recovery ofthe zinc. As beforedescribed, any metallic sulphate present `in thesolution in quantity sufficient to interfere with the recovery of thezinc may be removed by passing the solution through digesters, suchas83, Where such sulphate is removed by zinc oxide.

If in dissociatmfJr the iron sul Jhates 1n 88 rthe temperature should beinadvertently permitted to rise high enough to produce either Y basiczinc sulphate, 3Zn0 (S03) 2, or zinc oxide, the Water used in the vessel90 is aciduvlated todissolve 4the basic zincsulphate and the zinc oxideout of the iron oxides so that the Zinc may be recovered.

This second method of segregating the iron from the other sulphates isadvantage ous because of the large amount of iron present in the form offerrous, ferric and basic ferrie sulphates which give up their sulphuricanhydride at temperatures below that at which the zinc sulphatedissociates, thus producing a large amount of S03 for use in the streamor for manufacturing sulphurie acid. The temperature employed should bebelow that at which S03 is dissociated into S02+0. A further advantageis economy in the recovery of the zinc, its cost being measured by theWashing at 90 and the electrolytic deposition of the zinc. This is themethod which is specifically shown in the flow sheet, Figs. 11 and 11a.

The third and most universal method of eliminating the iron is tooxidize and hydro lyze the sulphates of iron upon the hydrolyzing plain,the stream with its various sulphates being discharged thereon andallowed to flow in all directions down over the steps, becoming more andmore shallow until it is a mere film and the flow ceases. Under theseconditions, the ferrous sulphate rapidly oxidizes into ferrie and basicferrie sulphate in accordance with reactions (6), (13), and

ing with two additional molecules of Water into the sesquioxide of ironthus The hydrolyzed and oxidized iron produced by reactions (6), (13),(24) and (25), comprising Fe(0H)3 and Fe203, piles upon the hydrolyzingplain While the resulting sulphuric acid joins the remaining sulphatesand eventually gravitates with them into the gutter at the base of theplain, from which they may be drained into a conveniently located sumpin which the zinc sulphate crystallizes. In Fig. l, such a sump isindicated in dotted lines at 36a, the same being located at the lowerend of the gutter 36. The zinc sulphate crystals from the sump may thenbe dehydrated and dissociated for the production of S03 and Zn0, theformer being conducted to its appropriate pipe 341- for use in the tubes28 and injectors 31, or for the production of sulphuric acid, the Zn0being retained for use in the digesters 83 in case the nickel and cobaltbecome-troublesome. However, it is not necessary to employ the sump 36a,since the zinc sulphate crystallizes in the gutter 36 and may betransferred directly therefrom to a dehydrator and dissociator,

such as 87 and 88, the S03 produced by dissociation being fed ybackthrough the `pipe 89 sedes-i i. leached out by spraying the hydrolyzedmass with weak sulphuric acid, being thus returned to the sulphate formso that they may reach the gutter 36.

' rllhe iron oxides left in the vessel 90 in carrying out the secondmethod and the iron l5 hydroxides left on the hydrolyzing plain inthethird method may be treated in any suitable ina-nner for the recoveryof their iron values.

`Whatever S03 is produced that is not required to maintain the acidstrength and temperature of the stream is converted into sulpliuric andfuming sulphuric acid. This surplus S03 is led from the pipe 89 at apoint 93 to the towers 94-94a which are connected in series, as shown.IThe S03 is caused to advance counter to a current of water, which issupplied from a source 95 to the end tower 94a. The water absorbs theS03, producing sulphuric acid in the tower 94a, the acid strengthincreasing until, in the tower 94 where the S03 is introduced, theliquid is fuming sulphuric acid. The latter is then transferred to asuitably constructed receptacle 96.

Should the quantity of cobalt and nickel in the solution be too great toremove from the zinc solution by digesting a large amount of zinc oxidein the solution in the digesters 83, an alternate method of recoveringthe zinc from the cobalt and nickel is to keep the solution stronglyacid, which will hold the cobalt and nickel in solution while very purezinc crystals form. As soon as any cobalt f or nickel begins tocontaminate the zinc-crystals being deposited, the solution is withdrawnand fractional crystallization is practiced to separate the remainingzinc from the cobalt and nickel. The ultimate cobalt and nickel solutionis treated in the well known way by rendering it basic and precipitatingthel cobalt with sodium hypoclilorite and the nickel with sodiumcarbonate, which effects their separation.

This process may be employed in the prof duction of copper sulphate,zinc sulphate,

and ferrous and ferrie sulpliates. However, its chief use is in theproduction of the sulphate of hydrogen (H2S04). It will be noted thatthe only places in the system where sulphur escapes concentration intothe sulphate of hydrogen is in the distillation of the .feeble vatom ofsulphur from pyrite, in the insoluble Vsulphate of lead, intheaccidental losses, such-as the escape ofSO2 and ILS from the solution,and in the sulphur which is precipitated andl wasted. vAfter all of thebranches of the process are in full'operation and there is no furthercapacity to utilize the accumulating S03 ion in the stream, all of thesulphur of the sulphides that are converted into sulphates (with theexception of lead sulphate) is eventually dissociated from its metalbases and is combined with H20 to pro-` duce the sulphate H2S04. Iprefer to concentrate the S03 ions into ferricsulphate, which breaksinto Fe203 and S03 at temperatures below the dissociating point of S03into Iclaim: v f f l. The herein described method which comprisesmaintaining a flowing stream of liquid sulpliating material in anelongated and unobstructed trough, the strength of the said materialincreasing in the direction of c the source of the stream, introducing amixture of two sulphides in finely divided condition into said streamata point where the strength of the materialv is sulicient to attack themore susceptible sulphide only, thus converting it into thecorresponding sulphate which dissolves in the stream and flows with it,and movingcthe remaining and less susceptibleV sulphide up the streaminto a region where the sulphating strength of the material issufficient to attack itV and convert itinto its corresponding sulphatewhich dissolves in the stream, whereby the sulphates are'separated inthe Astream and made available for separate treatment for the recovery'of their re- ,i

spective values.

2. The herein described method which comprises maintaining a flowingstream of liquid sulphating material in an elongated and unobstructedtrough, the strength of the said material increasing in the direction ofthe source of the stream,'introducing a mixture of two sulphides infinely divided condition into said stream at a point where the strengthVof the material is suflieient to attack iio the more susceptiblesulphide only, thus converting it into the correspondingI sulphate whichdissolves inthe stream and Hows with it, moving Athe remaining and lesssusceptible sulphide up the stream into a region where iis thesulphating strength of the material is sutlicient to attack it andconvert it into its corresponding sulphate which dissolves'in thestream, whereby the sulphates are separated in the stream, treating theseparated sul- ...in

phatesfor the recovery of their respective values,l and injecting theacid contents of the sulpliates into the bottom of the stream to movethe less susceptible sulphide therein and to maintain the sulphatingstrength of the stream. y 3. The herein described method which comprisesmaintaining a flowing stream of liquid sulphating material in anelongatedopen and unobstructed trough, the strength of the said materialincreasing in the direction lofthe source of the stream, maintaining theliquid in the stream at substantially its boiling point, introducing amixture of iron sulphide inthe form of FeS2 and copper sulphide into thestream, said sulphides being in iinely divided condition, moving thecopper sulphide up the stream into a zone Where the strength of thesulphating material is sufficient to convert itinto the sulphate ofcopper, withdrawing the. said copper sulphate from the stream, removingthe FeSg from the surface of the stream, heating it to convert it intoFeS, introducing the FeS into the removed copper sulphate to convert thelatter into/FeSO4 and CnS, removing the CnS by liltration, treating theCUS to reconvert it intocopper sulphate, recovering the copper from thelatter, converting the FeSOi into F`e2(SO4)3 and introducing theFegfSOQS into the stream to maintain its temperature and sulphatingstrergth.

4. The herein described method which comprises maintaining a flowingstream of liquid sulphating. material, introducing' mixed sulphides i-nlinely divided condition into said stream, converting the varioussulphides in the stream into` the corresponding sulphates, removingcertain of said sulphates from the stream for recovery of their metalvalues, flowing the stream with its remaining sulphates in solution ontoan extended plain over Which the stream may spread and on whichsulphates may crystallize, removing the sulphate crystals from theplain, dehydrating the removed crystals, dissociating certain of thecrystals into the correspondin g metal oxide and sulphuric anhydride,and injecting the sulphuric anhydride into the stream to maintain theacid strength of the latter and to -agitate the sulphidesr therein Whileundergoing sulphatization.

5. The herein described method Which com prises maintaining a flowingstream of liquid sulphating material, introducing mixed sulphides ininely divided condition into said stream, said sulphides containingsulpliides of iron and zinc, converting the various sulphides in thestream into the corresponding sulphates, removing certain of saidsulphatcs lfrom the stream for recovery of their metal values, flowingthe stream With its iron and zinc sulphates in solution onto an extendedplain over which the stream may spread and on which the iron and Zincsulphates may crystallize, removing the iron and zinc sulphate crystalsfrom the plain, dehydrating said crystals, dissociating the ironsulphate crystals to form iron oxide and sulphuric anhydride, injectingthe sulphuric anhydride into the stream to maintain the yacid strengthof tho latter and to agitate the sulphides therein While undergoingsulphatization, Washing the zinc sulphate from the iron oxide andrecovering the zinc from its sulphate.

6. The herein described method Which comprises maintaining a flowingstream of liq.- uid sulphating material, introducing mixed sulphides infinely divided condition into said stream, converting the varioussulphides in the stream into the corresponding sulphates, flowing thestream With certain of its sulphates in solution onto an extended plainover which the stream may spread and on which the sulphates maycrystalline, and removing the crystals from the plain for treatment forthe recovery of their metal values.

7. The herein described method which comprises maintaining a flowingstream of liquid sulphating material, introducing mixed sulphides infinelydivided condition into said stream, converting the varioussulphides in the stream into the corresponding sulphates, flowing' thestream With certain of its sulphates in solution onto an extended plainover which the stream may spread and on which sulphates may crystallize,removing the crystals from the plain, dehydrating all the removedcrystals and dissociating the crystals of the sulphate of one metal intothe corresponding metal oxide and S03, injecting such of the said `S03into the stream as is required to maintain its sulphating strength, andcombining the remainder of the S03 With Water to produce sulphuric acid.

8. The herein described method which co1n prises maintaining a flowingstream of liquid sulphating material, introducing mixed sulphides inlinely divided condition into said stream, converting the varioussulphides in the stream into the corresponding sulphates, the sulphatesbeing dissolved in the stream, removing certain of the dissolvedsulphates from the stream for recovery of their metal values, flowingthe stream With other of its dissolved sulphates onto an extended plainover which the stream may spread and on which sulphates may crystalline,removing the crystallized suiphates from the plain, dehydrating all ofthe removed crystals, dissociating the crystals of the sulphate of onemetal into the corresponding metal oxide and SOS, and injecting the S03into the stream to maintain its sulphating strength.

9. The herein described method Which comprises maintaining a flowingstream of liquid sulphating material, introducing mixed sulphides infinely divided condition into said stream, the mixed sulphidescontaining copper sulphide, converting the various sulphides in thestream into the corresponding sulphates, the sulphates being dissolvedin the stream, removing the dissolved copper sulphate from the streamfor recovery oi its metal value, flowing the stream with other of itsdissolved sulphates onto an tended plain over which the stream mayspread and on which the contained sulphates may crystallize, removingthe crystallized sulphates from the plain, dehydrating Vall of lintosaid stream, said sulphides containing the sulphides of copper, iron andzinc, the said sulphides being introduced into the stream intermediateits ends, converting the sulphides of iron and zinc into thecorresponding sulphates which become dissolved in the stream and flowwith it, moving the copper sulphide up the stream from the place ofintroduction of the sulphides, converting the copper sulphides intocopper sulphate, treating the copper sulphate for recovery of its metalvalues, flowing the stream with its iron and zinc sulphates in solutiononto an extended plain over which the stream may spread and on whichthel iron and zinc sulphates may crystallize, removing the iron and zincsulphate crystals from the plain, dehydrating said crystals,dissociating the iron sulphate crystals to form iron oxide and sulphuricanhydride, the dissociating tempera-V ture being maintained. below thatat which the zinc sulphate crystals would dissociate, injecting thesulphuric anhydride intofthe stream in an amount suliicient to maintainthe acid strength of the latter, and combining the remainder lof the S03with Water to produce sulphuric acid.

11. The` herein described method which comprisesmaintaining a flowingstream of liquid sulphating material, introducing mixed sulphidesinlinely divided condition into saidstream, said sulphides containingthe sulphides of iron, zinc, cadmium and nickel, converting saidsulphides in the stream into the corresponding sulphates, removing thesulphates of cadmium and nickel from the stream, flowing the stream withits iron and zinc sulphates in solution onto an extended plain overwhich the stream may spread and on which the iron and zinc sulphates maycrystallize, removing the iron and Zinc sulphate crystals from theplain, dehydrating said crystals, dissociating the iron sulphatevcrystals to form iron oxide-and sulphuric anhydride, 'the temperatureused in dissociating the iron sulphate crystals being lower than thatrequired to dissociate the zinc sulphate crystals, injecting thesulphuric anhydride into the' stream to maintain the strength of theliquid and toagitate the sulphides therein while'undergoing sulphatiza-12. The herein-described method which Y comprises maintaining a iowingstream'of liquid sulphating material, introducing Y mixed sulphides innely divided condition into said stream, said sulphides containingsulphides of iron, Zinc, cadmium, arsenic, antimony and bismuth and someof the iron sulphides being FeS2, converting thefvarious sulphides,except the FeS2, in the stream into the corresponding sulphates whichbecome dissolved in the stream and iow with it, removing the FeS2` fromthe stream, heating the removed FeS2 to drive off its feeble atom of Sand produce FeS, using FeS thus obtained to precipitate the sulphides ofcadmium, arsenic, antimony and bismuth, removing the said precipitatesfrom the stream,

flowing the stream with its iron and zinc sulphates in solution onto anextendedk plain over which the stream may spread and on which the ironand zinc sulphates maycrystallize, removing the iron and zinc crystalsfrom the plain, dehydrating said crystals,

dissociating the iron sulphide crystals to form iron oxide and sulphuricanhydride, the temperature used in dissociating the iron sulphatelcrystals being maintained below that at which the Zinc sulphatecrystals dissociate, injecting the sulphuric anhydride into ythe streamto maintain the acid strength of the" latter, separating the zincsulphate from the iron oxide and recovering the'zinc from its sulphate.

13. The herein described method which comprises maintaining a flowingstream of liquid sulphating material,introducingmixed sulphidesin finelydivided condition into said stream, said sulphides containing sulphidesof iron, zinc, cadmium, arsenic, antimony and bismuth and some of theiron 'sulphides being Fesz, converting the various sulphides, except theF eS2, in the stream intothe corresponding sulphates which becomedissolved in the stream and flow with it, removing the FeS2 from thestream, heating the removed FeS2 to drive oil its feeble atom of S andproduce FeS, introducing FeS thus obtained into the flowing stream toprecipitate the sulphides of cadmium, arsenic, yantimony and bismuth,removingfthe said pre-y cipitates from the stream, owing the stream withits giron and zincv sulphates in solution onto an extended plain overwhich the stream may spread and on which the iron and zinc` sulphatesmay crystallize, removing the iron and zinc crystals fromthe plain,dehydrating said crystals, dissociating the iron sulphide crystals toform iron oxide and sulphuric anhydride, the temperature lused 'in ndissociating the iron sulphate crystals being maintained below that atwhich the zinc sulphate crystals dissociate, injecting such of thesulphuric anhydrate into the stream as is necessary to maintain the acidstrength of the latter and to agitate the sulphides there- Ain `.whileundergoing sulphatization, combining the remainder of the sulphuricanhydride with Water to produce sulphuric acid, washing the Zincsulphatefrom the iron oxide, recovering the zinc from its sulphate inelectrolytic cells, and returning the electrolyte to the stream.

14;. The herein described method which comprises maintaining a flowingstream of liquid sulphating material in an elongated, unobstructed andopen trough, introducing -a mixture of sulphides in finely dividedcondition into said stream intermediate` its ends, the Vlighter and moreeasily sulphated portions of the vsulphides flowing with the upperportion of the stream down the latter until they are sulphated anddissolved in the stream, injecting acid-forming materials into thebottom of :the stream to agitato the heavier and more inert sulphideswhich sink to kthe bottom and to cause them to move up the stream in adirection counter to the iow of the liquid in the upper part thereof,Vand sulphating said heavier sulphides and dissolving them in portionsof the stream other than those portions where the lighter sulphides weresulphated and dissolved, whereby the various sulphates are separated inthe stream for individual treatment.

15. The herein described method which comprises maintaining a flowingstream of liquid sul-phating mate ial in `an elongated, unobstructed andopen trough, introducing a mixture ot' sulphides in finely dividedcondition into said stream intermediate its ends, the lighter and moreeasily sulphated portions of the sulphides flowing with the upperportion of the stream down the latter until they are sulphated anddissolved in the stream, agitating the heavier and more inert sulphideswhich sink to the bottom and causing them to move up the stream in adirection counter to the flow oit the liquid in the upper part thereof,sulphating said heavier snlphides and dissolving them in portions of thestream other than those portions where the lighter lsulphides weresnlphated and dissolved, whereby the various sulphates are separated inthe stream, treating the separated sulphates for the recovery of theirrespective metal values, and injecting the acid contents of thesulphates into the bottom of the stream to agitate and move the saidVheavier sulphides up the stream and to maintain the strength ot' thelatter.

16. The herein described method which comprises maintaining a flowingstream et liquid sulphating material in an elongated trough, the acidstrength of the said material increasing in the direction of the sourceof the stream, introducing a mixture of sulphides in finely dividedcondition into said stream wherein the various sulphides are dissolvedand the sulphates separated 'from one another in the stream, removingcertain of the sulphatesfrom the stream, -lowing the moved :t'orm thestream and the crystallized sulphates from the plain for the recovery oftheir respective metal values with the resultant `production ofsulphuric anhydride, ferric sulphate and sulphuric acid and injectingthe said sulphuric anhydride, lerric sulphate,

`sulphuric acid, air and water into the bottom of the stream whereverrequired to maintain the `sulphating strength and temperature oi' thestream and to move the sulphides in the bottom of the trough aga-instthe current of the stream therein into regions where the liquid isstrong enough to sulphate them.

17. The herein described method which comprises maintaining a flowingstream of liquid sulphating material in an elongated and unobstructedtrough, introducing a mixture of sulphides in finely divided conditioninto said stream at a point intermediate its ends, the lighter and moreeasily sulphated particles of the sulphides remaining in suspension inthe stream an-d being carried with it below the point of introduction ofthe sulphides where they are sulphated and their sulphates dissolved,moving the heavier particles of the sulphides up the stream Jfrom thepoint of introduction of the sulphides into regions where they becomesulphated, dissolved and separated from one another, and treatingthe'sulphates for the recovery of their respective "metal values.

18. The `herein described method which comprises maintaining a flowingstream of liquid sulphating material in an elongated and unobstructedtrough, introducing a mixture of sulphides in finely divided conditioninto said stream at a point intermediate its ends, the lighter and moreeasily sulphated particles of the sulphides remaining in suspension inthe stream and being carried with it below the point of introduction ofthe sul-` phides where they are sulphate-d and their sulphatesdissolved, moving the heavier particles of the sulphides up the streamfrom the point of introduction of the sulphidcs into the latter and intoregions where they become sulphated, dissolved and separated from oneanother, treating the sulphates for the recovery of their respectivemetal values, and injecting the acid contents of the sulphates into thebottom of the stream at points where needed to maintain the sulphatingstrength of the liquid and to cause the heavier particles of thesulphides to move up the stream.

19.` The herein described method which comprises maintaining in anelongated and unobstructed trough a flowing stream of liquid sulphatingmaterial, the acid strength of which increases in the up-streamdirection, introducing into said stream, intermediate its ends, amixture of comminuted sul- T phides containing the sulphides of copper,sulphides which are more easily attacked by the sulphating material thanis the copper sulphide and other sulphides which are more resistant tothe attack than is the copper sulphide, sulphating the more easilyattacked sulphides, f dissolving their sulphates and iowing the latterdown the stream belovsTA the point of introduction of the sulphides,moving the copper sulphide up the stream from the point of itsintroduction into a part of the stream Where the acid strength issufficient to attack and sulphate it, dissolving the copper sulphate inthe stream and treating it for the recovery of its metal value, movingthe more resistant sulphides up the steam beyond the point Where thecopper sulphide was sulphated into respective parts Where the acidstrength of the liquid is suiiicient to sulphate them, moving certain ofthe sulphates beyond the head of the stream and treating them for therecovery of their respective metal values,

and introducing the acid contents of the sev-V eral treated sulphatesback into the stream to maintain its acid strength.

20. The herein described method Which comprises maintaining a body ofliquid sul phating material, the acid strength of which varies frompoint to point in the body; introducing into said body a mixture ofmetallic sulphides containing the sulphides of iron and zinc, moving thesulphides in said body to points Where the strength of the material issuicient to attack them; sulphating the various sulphides into thecorresponding sulphates, crystallizing the sulphates of iron and zincand dehydrating the mixed crystals, heating the dehydrated crystals to atemperature suicient to dissociate the iron sulphate crystals only,formingiron oxide and S03, dissolving the zinc sulphate crystals,separating the dissolved zinc sulphate from the iron oxide, treating theZinc sulphate for the recovery of its metal value, and introducing suchpart of the S03 into the body at its various points as is required tomaintain its acid strength, at those points.

In testimony whereof I have signed my name to this specification.

GEORGE CAMPBELLY CARSON.

